Assigxoimo himself



T. A. EDISON.

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THOMAS A. EDISON, or NEWARK, NEW

JERSEY, ASSIGJOR r0 nmsntr AND GEORGE HARRINGTOI, 0F V ASHINGTON, D. C.

Specification forniing part oi' Letii-rs Patent No. 1 2.7,3h4i, datedFebruary 10,1874; application filed July 29, 1873.

To all whom it may concern:

Be itknown that I, THOMAS i. En sox, of Newark, in the county of Essexand State of New Jersey, have invented an Improvement in Circuits forChemical Telegraphs', of which the following is a specification:

This invention is for use in automatietclegraphing in which perforatedpaper is employed in transmitting, and chemical paper in lei-hiring, themessage.

The receivingand transmitting instruments are in shunt-circuits from themain line, and in each circuit there is a battery. These batfcries actin opposition to each other,-and produce no eifectat thercceiving-instrumeiit when the shunt-circuit is broken at thetransmitter. When this circuit is closed, the current from the batteryof the transmitter is short -eircuitcd, and does not pass over the line.This destroys the balance of electrical tension, and the battery at thereceiving end of the line acts upon the chemical paper and makes themark.

In the diagrannthe tralisniitting-instrunlent is represented at u, andthe l'eceh ingdnstrument at b. and these are of usual character fortransmitting by perforated paper, and rewiring by chemical paper. Thetransmitter is in the circuit 3 to the battery 0, and the receiver is inareireuit, 4, to the battery d, and the main line 2 is connected tothese circuits, 3 and 4. -The poles of the batteries 0 d are placed sothat said batteries oppose each other, and when the strip of perforatedpaper intervenes between the stylus and drum of the transmitter thecircuit 3 is broken, and the current from the battery 0, over the line2,and through the receiving-instrument b to the earth, is equaled by thecurrent from the battery (I, and hence no mark is made upon the chemicalpaper of the receiviilg-instrument b. The rheostat c is introduced inthe shunt-circuit 4, and should be adjustable, so that the electric energy from the battery d mag; balance that from the line 2, and preventdecomposition in the chemical paper.

When the stylus or roller ot' the transmitter enters a pcrtoration inthe strip of paper, then the short circuit 3 from the 1m ttery c isclosed, and the electricity passes bat little upon the line 2. Thebattery (I is now unbalanced, and its current, passing by the circuit 4through the stylus of the receiver, nmkcs the mark upon the chemicalpaper.

1. claim as my invention The circuit 4 from the battery (I, in which thereceiving-instrument b is placed, in combination with the opposing-linecircuit 2 and the shunt-circuit- 3 at the rcceiving-instrument, in whichare placed the trai1smittiiig-instrunzieiit and battery, as and forthepurposes set forth. Signed by me this 24th day of March, A; l). 1873.

THOMAS A. unison.

Witnesses:

(3-130. '1. PINCKNEY, CHAS. H. SMITH.

